Effect of Infusion Temperature on Color and Antioxidant Properties in Goji Berry (Lycium Babarum) and Saffron (Crocus Sativus L.) Tea

Loh, Shu Jean (2021) Effect of Infusion Temperature on Color and Antioxidant Properties in Goji Berry (Lycium Babarum) and Saffron (Crocus Sativus L.) Tea. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Both goji berry (Lycium Babarum) and saffron (Crocus sativus L.) are chosen in this study because they possess antioxidant effects that benefit consumer’s health. The present study is aimed to study the effects of infusion temperatures on the color and antioxidant components (total polyphenols content (TPC) and antioxidant activity) of the two herbs. The goji and saffron tea were made using hot water at different infusion temperatures (60°C, 70°C, 80°C, 90°C and 100°C). The three physicochemical tests (color, total polyphenol content (TPC) and DPPH scavenging activity) were conducted using (L*, a* and b*), Folin-Ciocalteu (FC) method and DPPH assay, respectively. The results indicated the total polyphenol content and DPPH scavenging activity of goji and saffron tea increased with increased infusion temperature. For each tea samples, Infusion temperature showed a significant effect on the three physicochemical test parameters but the significant difference is not observed between the temperatures, except between the lowest and highest temperature at p < 0.05. However, the significant difference is observed in the three physicochemical test parameters between the two tea samples. It showed that the overall color (L*, a* and b*) of saffron tea was higher than goji tea but the overall TPC and DPPH scavenging activity were higher in goji tea for each infusion temperature. The Pearson correlation showed a strong positive correlation between TPC and DPPH scavenging activity at p < 0.01. This showed that when total phenolic compound increase, the radical scavenging activity also increases, indicating that the antioxidant activity is also greater. Overall, 100°C is the optimum temperature that gave the highest antioxidant activity in goji tea and saffron tea due to their highest TPC (13.40 ± 0.03 and 7.82 ± 0.25 mg GAE/100g respectively) and DPPH scavenging activity (10.94 ± 0.23 and 12.07 ± 0.60% respectively) at this temperature.